Multiple-input and multiple-output (MIMO) is a technique for using multiple transmit and receive antennas to multiply the capacity of a radio link and exploit multipath propagation. MIMO is a component of wireless communication standards such as Wi-Fi (IEEE 802.11n & IEEE 802.11ac), WiMAX (4G) and Long Term Evolution (4G). Full dimension MIMO (FD-MIMO) involves multiple transmit and receive antennas that can form beams in both horizontal and vertical directions such that the beams can cover anywhere in three dimensional space in the vicinity of the multiple antennas.